1. Field of the Invention
The present invention relates to a thin film magnetic head. More particularly, the present invention relates to a floating magnetic head having the thin film magnetic head.
2. Description of the Related Art
Magnetoresistive thin film magnetic heads include AMR (Anisotrophic Magnetoresistive) and GMR (Giant Magnetoresistive) heads. An AMR head has an element exhibiting a magnetoresistive effect. A GMR head has an element exhibiting a giant magnetoresistive effect.
In a GMR head, the element exhibiting the giant magnetoresistive effect has a multilayer structure. Among several types of multilayer structures creating the giant magnetoresistive effect, a relatively simple structure exhibiting a high rate of change in resistance with an external magnetic field is the structure of a spin-valve thin film magnetic element. This structure has at least a free magnetic layer, a pinned magnetic layer, and a nonmagnetic layer. Such spin-valve thin film magnetic elements include single and dual spin-valve thin film magnetic elements.
In addition, there are different systems for orienting the magnetization direction of the free magnetic layer including hard and exchange bias systems. In recent years, the exchange bias system has become more widely used because it is adaptable to the track narrowing associated with increases in magnetic recording density.
FIG. 31 shows a thin film magnetic head 501 comprising an exchange bias system.
FIG. 32 shows the structure of a principal portion of a floating magnetic head 500 comprising the thin film magnetic head 501 shown in FIG. 31 and a write inductive head 503, as viewed from the surface facing a medium.
The floating magnetic head 500 comprises the thin film magnetic head 501 and the inductive head 503, which are laminated on the trailing end 504a of a floating slider 504.
The thin film magnetic head 501 is a reproduction-only magnetic head, and comprises a pair of shield layers 507 and 508 laminated on both sides of a spin-valve thin film magnetic element 502 in the direction of the thickness. Insulating layers 505 and 506 are provided between the spin valve thin film magnetic element 502, and the shield layers 507, 508 respectively.
In FIGS. 31 and 32, the Z direction is the movement direction of a magnetic recording medium. The Y direction is the direction of a leakage magnetic field from the magnetic recording medium. The X1 direction is the direction of the track width of the thin film magnetic head 501 and the inductive head 503.
As shown in FIG. 32, the floating magnetic head 500 comprises an insulating layer 509 laminated on the trailing side end 504a of the floating slider 504. The lower shield layer 508, the spin-valve thin film magnetic element 502, the upper shield layer 507, a gap layer 510, and an upper core layer 511, are laminated in turn on the insulating layer 509.
As shown in FIG. 32, the thin film magnetic head 501 comprises the spin-valve thin film magnetic element 502, and the shield layers 507 and 508. The inductive head 503 comprises the lower core layer (upper shield layer) 507, the gap layer 510 and the upper core layer 511.
In the inductive head 503, the upper and lower core layers 511 and 507 are arranged opposite to each other with the gap layer 510 provided therebetween to form a write magnetic gap G1.
The upper shield layer 507 is also the lower core layer of the inductive head 503.
The spin-valve thin film magnetic element 502 is a bottom-type single spin-valve thin film element comprising an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer, which are laminated in turn.
In the spin-valve thin film magnetic element 502, the insulating layer 506 is made of Al2O3 and is laminated on the lower shield layer 508. An antiferromagnetic layer 512, a pinned magnetic layer 513, a nonmagnetic conductive layer 514 made of Cu or the like, and a free magnetic layer 515 are laminated in turn on the insulating layer 506.
A pair of bias layers 516 are laminated on the free magnetic layer 515 with a pair of ferromagnetic layers 518 provided therebetween. The ferromagnetic layers 518 are made of, for example, a NiFe alloy and are spaced along the X1 direction shown in FIG. 31.
A pair of conductive layers 517 made of Cu are laminated on the bias layers. An insulating layer 505 made of Al2O3 is laminated to cover the conductive layers 517 and the free magnetic layer 505. The upper shield layer 507 is laminated on the insulating layer 515.
The antiferromagnetic layer 512 comprises an antiferromagnetic material such as a PtMn alloy, or the like. The antiferromagnetic layer 512 is laminated in contact with the pinned magnetic layer 513 so that an exchange coupling magnetic field (exchange anisotropic magnetic field) is exhibited in the interface between the pinned magnetic layer 513 and the antiferromagnetic layer 512. The magnetization direction of the pinned magnetic layer 513 is pinned in the Y direction as shown in the drawings.
Each of the bias layers 516 is made of an antiferromagnetic material such as an IrMn alloy or the like. The bias layers 516 are laminated in contact with the ferromagnetic layers 518 so that an exchange coupling magnetic field (exchange anisotropic magnetic field) is exhibited in each of the interfaces between the bias layers 516 and the ferromagnetic layers. The magnetization direction of the free magnetic layer 515 is oriented in the X1 direction shown in the drawings by the exchange coupling magnetic field. As a result, the free magnetic layer 515 is put into a single magnetic domain state to suppress Barkhausen noise.
Therefore, the magnetization direction of the free magnetic layer 515 crosses the magnetization direction of the pinned magnetic layer 513.
In addition, the pair of bias layers 516 are laminated with a space therebetween to produce a portion where the bias layers 516 are not laminated on the free magnetic layer 515. This portion serves as a track portion G2 of the thin film magnetic head 501.
In the thin film magnetic head 501, the magnetization direction of the free magnetic layer 515 is oriented in the X1 direction and changes with a leakage magnetic field from a recording medium such as a hard disk. The magnetization of the pinned magnetic layer 513 is pinned in the Y direction as shown in the drawings. Accordingly, the changing orientation of the free magnetic layer 515 changes the electric resistance of the spin-valve thin film magnetic element. The voltage changes based on the change in the electric resistance, thus detecting the leakage magnetic field from the recording medium.
In the conventional thin film magnetic head 501, as shown in FIG. 31, the pair of bias layers 516 and the conductive layers 517 are laminated on the free magnetic 515. A step 505a occurs in the insulating layer 505 near the write track portion G2. This step 505a is patterned by the gap layer 510 through the upper shield layer 507 to warp the shape of the write magnetic gap G1 of the inductive head 503, as shown in FIG. 32. Consequently, a magnetic recording pattern recorded on the magnetic recording medium is also warped, thus causing potential errors during reproduction.
In manufacturing the floating magnetic head 500, a plurality of thin film magnetic heads 501 and inductive heads 503 are formed on a substrate by a thin film deposition technique. The substrate is cut. To determine the gap depth, the medium-facing surface must be polished with a grinding stone or the like. Namely, the surface of the drawing of FIG. 32 is the polished surface.
In the conventional thin film magnetic head 501, smearing occurs during polishing. The grind stone causes small portions of the polished surfaces of the shield layers 507 and 508 which are made of metal, to extend on the polished surfaces. The extended portions of the shield layers 507, 508 cause tongue-like sags 507a and 508a. The tongue-like sags 507a and 508a cross the insulating layers 505, 506 and reach the free magnetic layer 515, the antiferromagnetic layer 512, or the bias layers 516. This bridging causes a short circuit between the shield layers 507 and 508 and the spin-valve thin film magnetic element 502.
Particularly, there is a recent tendency to further thin the insulating layers 505 and 506 due to a need to narrow the gap length between the upper and lower shield layers 507 and 508xe2x80x94to comply with an increase in magnetic recording density. In this case, even when a little sag occurs, the sag readily reaches the antiferromagnetic layer and other layers. Consequently, the probability increases for a short-circuit between the shield layers 507 and 508 and the spin-valve thin film magnetic element 502.
In addition, the bias layers 516 and the conductive layers 517 are formed by a lift-off method. The bias layers 516 must be formed to a thickness of about 500 xc3x85 to securely orient the magnetization direction of the free magnetic layer 515. The conductive layers 517 must be formed to some thickness in order to flow a sensing current. In forming the bias layers 516 and the conductive layers 517 by the lift-off method, the incidence of burrs increases. As shown in FIG. 31, the burrs 519 contact the shield layer 507 through the insulating layer 505. This contact increases the probability of a short circuit between the shield layer 507 and the spin-valve thin film magnetic element 502.
Furthermore, each of the bias layers 516 is made of an antiferromagnetic material frequently having high resistivity. The conductive layers 517 are formed on the material having high resistivity. As a result, the sensing current cannot be efficiently applied to the free magnetic layer 515.
The present invention has been achieved for solving the above problems. An object of the present invention is to provide a thin film magnetic head with an essentially warp-free upper shield layer (the thin film magnetic head can be prevented from producing a great step in an upper shield layer). This prevents the occurrence of errors in magnetic recording by decreasing the warping of an inductive head formed on the upper shield layer. Another object is to improve yield by decreasing the probability of a short circuit between the upper or lower shield layers and the spin-valve thin film magnetic element. A further object of the present invention is to provide a floating magnetic head comprising the thin film magnetic head. In order to achieve these objects, the present invention uses the following construction.
A thin film magnetic head of the present invention has a spin-valve thin film magnetic element and a pair of shield layers laminated on both sides of the spin-valve thin film magnetic element in the direction of the thickness. The spin-valve thin film magnetic element has a lamination of a free magnetic layer, a nonmagnetic conductive layer, a pinned magnetic layer, an antiferromagnetic layer for pinning the magnetization direction of the pinned magnetic layer, a pair of conductive layers for supplying a sensing current to the free magnetic layer, and a pair of insulating bias layers for orienting the magnetization direction of the free magnetic layer. A projection is formed on one of the shield layers to project toward the spin-valve thin film magnetic element side. The pair of insulating bias layers are arranged on both sides of the projection in the direction of the track width.
The insulating bias layers are preferably provided between one of the shield layers and the free magnetic layer or the conductive layers.
In the thin film magnetic head, the pair of the insulating bias layers are arranged on both sides of the projection of one of the shield layers in the direction of the track width. The pair of insulating bias layers are partly or wholly buried in the one shield layer.
Therefore, a step produced on the side of the spin-valve thin film magnetic element, which contacts the other shield layer, can be decreased to prevent the propagation of the step to the other shield layer. For example, even when a gap layer and an upper core layer are laminated on the other shield layer to form an inductive head, no step occurs in the gap layer, thereby preventing the shape of a write magnetic gap from being warped.
In addition, since the pair of insulating bias layers are partly or wholly buried in one of the shield layers, even when the spin-valve thin film magnetic element is thinned to narrow the gap with increases in magnetic recording density, the insulating layers need not be thinned, and the magnetization direction of the free magnetic layer can securely be oriented in one direction.
Furthermore, the insulating bias layers having high insulation are laminated on one of the shielding layers. Even when the shield layers are partially extended to cause a sag in polishing the medium-facing surface for determining the gap depth, there is low probability the sag will reach the free magnetic layer across the insulating bias layers. Hence, there is a lower probability of a short circuit between one of the shield layers and the spin-valve thin film magnetic element.
In the thin film magnetic head of the present invention, preferably, an insulating layer is laminated at least on the projection. The surface of the insulating layer and the surfaces of the pair of insulating bias layers lie in the same plane. Accordingly, the free magnetic layer is laminated on the same plane.
In the thin film magnetic head, the insulating layer and the pair of the insulating bias layers form the same plane. Hence, a free magnetic layer is laminated on the same plane, thereby causing no step in the free magnetic layer.
In addition, since the free magnetic layer contacts the insulating bias layers, an exchange coupling magnetic field (exchange anisotropic magnetic field) is exhibited in each of the interfaces between these layers. The magnetization direction of the free magnetic layer is oriented in the direction of the track width by the exchange coupling magnetic field.
Therefore, in the thin film magnetic head, the magnetization direction of the free magnetic layer can be securely oriented in the direction of the track width to decrease Barkhausen noise.
The thin film magnetic head of the present invention further comprises a pair of ferromagnetic layers that are located on both sides of the free magnetic layer in the direction of the track width. The ferromagnetic layers are laminated on the pair of the insulating bias layers to exhibit an exchange anisotropic magnetic field so that the magnetization direction of the free magnetic layer is oriented by the exchange anisotropic magnetic field.
In manufacturing the thin film magnetic head, the insulating bias layers and the ferromagnetic layers are laminated in turn, thereby preventing impurity contamination of the interfaces therebetween. Also, the great exchange coupling magnetic field is exhibited in the interfaces between the insulating bias layers and the ferromagnetic layers. Hence, the magnetization direction of the free magnetic layer can be securely oriented in the direction of the track width by the exchange coupling magnetic field.
In addition, the insulating bias layers are provided between one of the shield layers and the ferromagnetic layers. Even when the shielding layers are partially extended to cause a sag during polishing of the medium-facing surface for determining the gap depth, there is a lower probability that the sag reaches the ferromagnetic layers across the insulating bias layers. Hence, there is lower probability of a short circuit between the shield layers and the spin-valve thin film magnetic element.
Furthermore, in the thin film magnetic head of the present invention, another projection is formed in the other shield layer to project toward the spin-valve thin film magnetic element side. The pair of the conductive layers are provided on both sides of the other projection in the direction of the track width.
Insulating layers are preferably provided between the conductive layers and the shield layers.
In the thin film magnetic head, the pair of conductive layers are provided on both sides of the other projection of the other shield layer. The pair of conductive layers are partly or wholly buried in the other shield layer through the insulating layer.
Therefore, even when the spin-valve thin film magnetic element is thinned to narrow the gap with increases in magnetic recording density, the conductive layers need not be thinned. Accordingly, the sensing current can be efficiently supplied to the free magnetic layer.
The thin film magnetic head of the present invention is characterized in that the pair of the conductive layers are spaced in the direction of the track width in contact with the free magnetic layer.
In the thin film magnetic head, the pair of the conductive layers are in contact with the free magnetic layer. Hence, the sensing current can be efficiently supplied to the free magnetic layer.
In accordance with another embodiment of the present invention, a thin film magnetic head comprises a spin-valve thin film magnetic element and a pair of shield layers laminated on both sides of the spin-valve thin film magnetic element in the thickness direction. The spin-valve thin film magnetic element has a nonmagnetic conductive layer, a pinned magnetic layer, and an antiferromagnetic layer, which are laminated on either side of a free magnetic layer in the thickness direction. The spin valve thin film magnetic element also has a pair of conductive layers for supplying a sensing current to the free magnetic layer and a pair of insulating bias layers for orienting the magnetization direction of the free magnetic layer. A projection is formed in one of the shield layers to project toward the spin-valve thin film magnetic element side so that the pair of insulating bias layers are arranged on both side of the projection in the direction of the track width.
The insulating bias layers are preferably provided between the one shield layer and the free magnetic layer or the conductive layers.
In this thin film magnetic head, the pair of the insulating bias layers are arranged on both sides of the projection of the one shield layer so that the pair of the insulating bias layers are partly or wholly buried in the one shield layer.
It is thus possible to decrease a step produced on the surface of the spin-valve thin film magnetic element, which contacts the other shield layer, thereby preventing the propagation of the step to the other shield layer. For example, even when a gap layer and an upper core layer are laminated on the other shield layer to form an inductive head, no step occurs in the gap layer. The shape of the write magnetic gap is not warped.
Since the pair of the insulating bias layers are partly or wholly buried in the one shield layer, even in a case in which the space between the spin-valve thin film magnetic element and the shield layers is decreased to narrow the gap with increases in the magnetic recording density, the insulating bias layers need not be thinned. No loss occurs in the bias magnetic field. Therefore, the magnetization direction of the free magnetic layer can be securely oriented in one direction.
In addition, the insulating bias layers having high insulation are laminated on one of the shielding layers. Even when the shield layers are partially extended to cause a sag in polishing the medium-facing surface for determining the gap depth, the probability of a short circuit between the shield layers and the spin-valve thin film magnetic element can be decreased because the shield layers are insulated by the insulating bias layers.
The thin film magnetic head of the present invention further comprises a pair of ferromagnetic layers that are located on both sides of the free magnetic layer in the direction of the track width. The ferromagnetic layers are laminated on the pair of the insulating bias layers to exhibit the exchange anisotropic magnetic field. The magnetization direction of the free magnetic layer is oriented by the exchange anisotropic magnetic field.
In manufacturing the thin film magnetic head, the insulating bias layers and the ferromagnetic layers are laminated in turn, thereby preventing impurity contamination of the interfaces therebetween. Also, the great exchange coupling magnetic field is exhibited in each of the interfaces between the insulating bias layers and the ferromagnetic layers so that the magnetization direction of the free magnetic layer can securely be oriented in the direction of the track width by the exchange coupling magnetic field.
In addition, the insulating bias layers are provided between one of the shield layers and the ferromagnetic layers. Even when the shielding layers are partially extended to cause a sag during polishing of the medium-facing surface for determining the gap depth, there is low probability that the sag reaches the ferromagnetic layers across the insulating bias layers, thereby decreasing the occurrence probability of a short circuit between the shield layers and the spin-valve thin film magnetic element.
In the thin film magnetic head of the present invention, preferably, an insulating layer is laminated on at least the projection. One of the antiferromagnetic layers, one of the pinned magnetic layers, and one of the nonmagnetic conductive layers are laminated on the insulating layer. The insulating bias layers are arranged on both sides of the projection, the one antiferromagnetic layer, the one pinned magnetic layer, and the one nonmagnetic conductive layer in the direction of the track width. Furthermore, the surface of the one nonmagnetic conductive layer and the surfaces of the pair of insulating bias layers lie in the same plane so that the free magnetic layer is laminated on the same plane.
In the thin film magnetic head, the insulating layer and the pair of the insulating bias layers form the same plane so that the free magnetic layer is laminated on the same plane, thereby causing no step in the free magnetic layer.
In addition, since the free magnetic layer contacts the insulating bias layers, an exchange coupling magnetic field (exchange anisotropic magnetic field) is exhibited in the interfaces between these layers. The magnetization direction of the free magnetic layer is oriented in the direction of the track width by the exchange coupling magnetic field.
Therefore, in the thin film magnetic head, the magnetization direction of the free magnetic layer can securely be oriented in the direction of the track width to decrease Barkhausen noise.
Furthermore, in the thin film magnetic head of the present invention, another projection is formed in the other shield layer to project toward the spin-valve thin film magnetic element side. The pair of the conductive layers are provided on both sides of the other projection in the direction of the track width.
Insulating layers are preferably provided between the conductive layers and the shield layers.
In the thin film magnetic head, the pair of the conductive layers are provided on both sides of the other projection of the other shield layer. The pair of the conductive layers are partly or wholly buried in the other shield layer through the insulating layer.
Therefore, even when the spin-valve thin film magnetic element is thinned to narrow the gap with increases in magnetic recording density, the conductive layers need not be thinned. The sensing current can be efficiently supplied to the free magnetic layer.
In the thin film magnetic head of the present invention, preferably, the other projection is formed in the other shield layer to project toward the spin-valve thin film magnetic element side. The other antiferromagnetic layer, the other pinned magnetic layer and the other nonmagnetic conductive layer are laminated on the other projection. In addition, the pair of the conductive layers are preferably arranged on both sides of the other projection, the other antiferromagnetic layer, the other pinned magnetic layer, and the other nonmagnetic conductive layer in the direction of the track width. The surface of the other nonmagnetic conductive layer and the surfaces of the pair of conductive layers preferably lie in the same plane so that the free magnetic layer is laminated on the same plane.
In the thin film magnetic head, the surface of the other nonmagnetic conductive layer and the surfaces of the pair of the conductive layers lie in the same plane so that the free magnetic layer is laminated on the same plane. Therefore, the conductive layers are brought into direct contact with the free magnetic layer to permit the efficient supply of the sensing current to the free magnetic layer from the conductive layers.
A floating magnetic head of the present invention comprises any one of the above-described magnetic heads provided on a slider.